Inhibitors of phosphoinositide-specific phospholipase C

ABSTRACT

Novel α-hydroxyphosphonate compounds which inhibit mammalian phosphoinositide-specific phospholipase-C. The compounds are potent anti-inflammatory and analgesic agents and may be useful for the treatment of cancer.

BACKGROUND OF THE INVENTION

Phospholipases C (EC 3.1.4.3) are a family of enzymes which hydrolyze the sn-3 phosphodiester bond in membrane phospholipids producing diacylglycerol and a phosphorylated polar head group. Mammalian phospholipase C (PLC) enzymes exhibit specificity for the polar head group which is hydrolyzed, i.e., phosphatidylcholine, phosphatidylinositol, etc. Recently, much interest has been generated in those PLC enzymes which selectively hydrolyze phosphoinositide lipids in response to receptor occupancy by agonist. Hydrolysis of phosphatidylinositol 4,5-bisphosphate generates two second messenger molecules; diacylglycerol, a co-factor required for activation of protein kinase C, and inositol 1,4,5-trisphosphate, a soluble second messenger molecule which promotes the release of intracellular nonmitochondrial stores of calcium (Berridge, Ann. Rev. Biochem., 56:159-193, 1987). The diacylglycerol released may be further metabolized to free arachidonic acid by sequential actions of diglycerol lipase and monoglycerol lipase. Thus, phospholipases C are not only important enzymes in the generation of second messenger molecules, but may serve an important role in making arachidonic acid available for eicosanoid biosynthesis in select tissues.

Mammalian tissues contain multiple distinct forms of phosphoinositide-specific PLC (Crooke and Bennett, Cell Calcium, 10:309-323, 1989; Rhee et al., Science, 244:546-550, 1989). It is proposed that each of the enzymes couple to distinct classes of cell surface receptors, i.e., PLC-β couples to thromboxane A₂, bradykinin, angiotensin and muscarinic receptors via G_(q) α or G₁₁ α (Shenker et al., J. Biol. Chem., 266:9309-9312 (1991); Gutowski et al., J. Biol. Chem., 266:20519-20524 (1991); Berstein et al., J. Biol. Chem., 267:8081-8088 (1992)), PLC-γ couples to growth factor receptors, etc. (Aiyar et al., Biochem. J., 261:63-70, 1989; Crooke and Bennett, Cell Calcium, 10:309-323, 1989; Margolis et al., Cell, 57:1101-1107, 1989; Wahl et al., Proc. Natl. Acad. Sci. USA, 86:1568-1572, 1989). Alignment of sequences from all groups reveals that the most conserved residues are clustered into two distinct regions (one of ˜170 amino acids and the other of ˜260 amino acids), designated the X and Y regions, respectively. PLCγ₁ also contains src-homology regions (SH2 and SH3) that appear to mediate the interaction between the enzyme and receptors with tyrosine kinase activity, such as the epidermal growth factor (EGF) receptor (Stahl et al. Nature, 332:269-272 (1988); Katan et al., Cell, 54:171-177 (1988)).

The PLC isozymes are activated by different mechanisms in response to stimulation of specific cell surface receptors. Coupling of PLCδ to specific receptors or downstream effectors has not been reported but this isozyme may be associated with mechanisms that regulate the tone of vascular smooth muscle. Activation of PLCβ is achieved by guanine nucleotide binding proteins of the Gq class.

To date, the cDNA for 6 distinct PI-PLC enzymes have been cloned. The enzymes range in size from 504 amino acids to 1250 amino acids, and are remarkably divergent considering that they exhibit similar biochemical properties. 4 of the 5 enzymes (PLC-β, PLC-δ1, PLC-δ2, and PLC-γ₁ ) contain two domains approximately 250 amino acids in length which exhibit between 50 to 80% sequence similarity. The marked differences in DNA sequences for the different PI-PLC enzyme allows the selective targeting of one PI-PLC enzyme, without affecting other enzymes using antisense technology. The human cDNA clone has been reported for PLC-δ2, (Ohta et al., FEBS Lett., 242:31-35, 1988) and PLC-γ1 (Burgess et al., Mol. Cell. Biol., 10:4770-4777 (1990)). The rest are rat cDNA clones. The genomic clones have not been reported for any of the PI-PLC enzymes.

All mammalian tissues which have been studied exhibit one or more PI-PLC enzymes. Generally, more than one enzyme exists in a single mammalian cell type. PI-PLC enzymes do exhibit tissue selectivity in their distribution. PLC-β is found predominantly in neural tissues and is the major enzyme in the brain. PLC-γ₁ is found in brain and many peripheral tissues. PLC-δ₂ is found in immune cells, and PLC-δ₁ appears to be predominantly in peripheral tissues. To date, a PI-PLC enzyme found exclusively in inflammatory cells has not been reported.

Point mutations of PLC-δ1 have been identified in the spontaneously hypertensive rat genome (Yagisawa et al., J. Hypertens. 9: 997-1004 (1991)). Biochemical studies have demonstrated the activation of PLC-δ1 (5 fold) in spontaneously hypertensive rats (Kato et al., J. Biol. Chem. 267:6483-6487 (1992)). The point mutations, situated in the putative catalytic domain, may be a major cause of the hypertension related phenomena of abnormal calcium homeostasis, a direct result of PLC-δ1 activation.

PI-PLC-δ2 appears to be an important enzyme in immunocompetent cells (Emori et al., J. Biol. Chem., 264:21885-21890). The protein is a moderately abundant protein comprising 0.1 to 0.05% of total cytosolic protein. No information is available concerning the genetic regulation of PI-PLC enzymes, mRNA or protein stability.

It has been established that a rapid synthesis of prostaglandins (PG) from arachidonic acid in macrophages usually accompanies inflammatory stimuli. Thus, inhibition of the release of arachidonic acid from macrophages would provide an effective control of PG synthesis and thereby inflammatory conditions. Recently, phospholiphase C has been characterized as an enzyme which is involved in the biosynthetic phosphatidylinositol-arachidonic acid-prostaglandin pathway. This finding is further substantiated by the observation that phospholipase C is inhibited by phenothiazine, a compound known to inhibit the stimulated release of arachidonic acid from macrophages and prostaglandins from platelets.

Activation of T cell antigen receptor (TCR/CD3) elicits a cascade of biochemical processes which are responsible for complex biological responses ranging from immune response to inflammation. The activation of PLCγ1 can also be achieved through the action of nonreceptor protein tyrosine kinases in response to certain cell surface receptors in leukocytes (TCR) (Park et al., Proc. Natl. Acad. Sci. U.S.A. 88:5453-5456 (1991)). PLCγ1 activation also occurs upon IgM ligation in B lymphocytes, IgE receptor (FcεRI) ligation in basophilic leukemia cells and IgG receptor (FcγRI and FcγRII) in monocytic cells (Liao et al., Proc. Natl. Acad. Sci. U.S.A. 89:3659-3663 (1992)). Thus, inhibition of PLCγ activity, may be of therapeutic value in the treatment of inflammatory conditions.

PLCγ is the only isozyme that is phosphorylated by activated tyrosine kinase growth factor receptors (Rotin et al., EMBO J., 11:559-567 (1992); Mohammadi et al., Mol. Cell. Biol., 11:5068-5078 (1992); Kim et al., Cell, 65:435-441 (1991)). Following growth factor stimulation, cytosolic PLCγ is extensively and rapidly phosphorylated in vivo (50-70% of the PLCγ molecules are modified within 5 minutes). This phosphorylation apparently induces the relocation of PLCγ to the plasma membrane where presumably it is better able to interact with its phospholipid substrates. In vitro studies utilizing enzyme that had previously been immunoprecipitated from cells suggest that the catalytic activity of the phosphorylated form of PLCγ1 is increased compared to that of the unphosphorylated form, although this effect also depends on the assay conditions. These results suggest that PLCγ may be an important component of mitogenic signal transduction. Furthermore, altered PLCγ activity may correlate with some disease states. For example, an increase in the concentration of PLCγ has been documented in cells derived from primary human breast carcinomas which also overexpress the EGF receptor (Arteaga et al., Proc. Natl. Acad. Sci. U.S.A., 88, 10435-10439 (1991)). Thus, inhibition of PLCγ activity, particularly of the activated form, may be of therapeutic value in the treatment of breast cancer.

In addition, PLCγ₁ has been localized in vivo (immunohistochemistry) through many layers of the epidermis from a diverse series of hyperproliferative skin conditions, such as psoriasis, seborrheic keratosies and acrochordons (Nanney et al., Cell Growth and Differentiation, 3:233-239 (1992)). Thus inhibition of PLCγ activity may be of therapeutic value in treating benign epidermal hyperplasia.

The recent demonstration that specific members of the Gq subfamily can activate different PLC-β isozymes (e.g. Gqα activates PLC-β1 ) (Smrcka et al., Science 25 1:804-807 (1991); Taylor et al., FEBS 286:214-216 (1991)) provides a connection of PLC-β to a number of transmembrane signal transduction pathways. NIH3T3 cells transfected with an activated mutant of Gqα display a fully transformed phenotype, are highly tumorigenic in athymic nude mice (Kalinec et al., Mol. Cell Biol. 12:4687-4693 (1992)) and display greatly enhanced phospholipase C (PLC-β) activity (DeVivo et al., J. Biol. Chem. 267:18263-18266 (1992)). Other mutatations in genes for the α subunits of some heterotrimeric G proteins (Lyons et al., Science 249:655-659 (1990); Vallar et al., Nature 330:556-558 (1987)), have been described and are associated with certain human endocrine tumours suggesting that activated G proteins may play a role in the oncogenic process. Thus, PLC-β in addition to PLCT may be associated with human cancer.

Accordingly, it is an object of this invention to provide specific and selective inhibitors of phospholipase C which can be potent anti-inflammatory and analgesic agents useful in the treatment of inflammatory conditions, including rheumatoid arthritis, emphysema, bronchial inflammation, osteoarthritis, spondylitis, lupus, psoriasis, acute respiratory distress syndrome, gout, fever, and pain.

It is also the object of this invention to provide inhibitors of phospholipase C which are pharmaceutical agents useful in the treatment of certain forms of cancer, including breast cancer, and other hyperproliferative disease states of the epidermis.

Another object of this invention is to provide pharmaceutical compositions to be used in the administration of the novel phospholipase C inhibitors.

Still a further object of this invention is to provide a method of controlling and treating inflammation and pain by administering an effective amount of the compounds of the instant invention in a mammalian species in need of such treatment.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. Plasmid pT5T-PLC4

A schematic depiction of the construction of plasmid pT5T-PLC4 is shown.

FIGS. 2a-2e. PLC γ₁ amino acid sequence and cDNA encoding sequence

The nucleotide sequence which encodes PLC γ₁ is shown along with the corresponding amino acids of PLC γ₁ which are provided underneath the cDNA sequence. The codons at 2833-2838 have been changed from the natural AGGAGG tandem to CGGCGG. (cDNA: SEQ.ID.NO.: 1; amino acid: SEQ.ID.NO.: 2)

FIGS. 3a-3e. cDNA encoding sequence which includes the epitope tag

Nucleotide sequence used for expression and purification of PLC γ₁ (1-3879; end indicated by "*") and the neighboring BamlI restriction site. The amino acid sequence of the longest open reading frame (1291 aa) is provided underneath the corresponding nucleotides. (cDNA: SEQ.ID.NO.: 3; amino acid: SEQ.ID.NO.: 2)

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to novel α-hydroxyphosphonate compounds of the structural formula I: ##STR1## or a pharmaceutically acceptable salt or ester thereof, wherein: R¹ and R² are independently selected from:

a) hydrogen; and

b) ##STR2## provided that if R¹ is hydrogen, R² is substituent b) and if R² is hydrogen, R¹ is substituent b); and

R³, R⁴, R⁵ and R⁶ are independently selected from the group consisting of:

a) hydrogen;

b) halogen;

c) C₁ -C₄ -alkyl;

d) C₁ -C₄ -alkoxy; and

e) hydroxy,

provided that at least one of R³, R⁴, R⁵ and R6 is a substituent other than hydrogen; or R³ and R⁴ or R⁴ and R⁵ are combined to form a --CH₂ CH₂ CH₂ CH₂ --diradical.

An embodiment of the instant invention is a compound having the formula I wherein the substitutents R¹ and R² are as described hereinabove and wherein substituents R³, R⁴, R⁵ and R⁶ are as described hereinabove provided, however, that both R³ and R⁴ are not methyl if R⁵ is hydrogen and R³ and R⁴ or R⁴ and R⁵ are not combined to form a --CH₂ CH₂ CH₂ CH₂ --diradical.

The alkyl substituents recited above denote straight and branched chain hydrocarbons of the length specified such as methyl, ethyl, isopropyl, isobutyl, etc.

The alkoxy substituent represents an alkyl group as described above attached through an oxygen bridge.

The term "halogen" represents substituents selected from iodide, chloride, bromide and fluoride.

Specific compounds of the instant invention include the compounds having the formula ##STR3## wherein

    ______________________________________                                         R.sup.3        R.sup.4     R.sup.5                                             ______________________________________                                         H              H           --OCH.sub.3                                         H              H           --Cl                                                H              --Cl        H                                                   --Cl           H           H                                                   H              H           --CH.sub.3                                          H              H           --OH                                                H              --Cl        --Cl                                                ______________________________________                                    

Other compounds of the instant invention include compounds having the formula: PG,10 ##STR4## wherein:

    ______________________________________                                         R.sup.3         R.sup.4   R.sup.5                                              ______________________________________                                         H               --Cl      H                                                    H               --OCH.sub.3                                                                              H                                                    H               --CH.sub.2 CH.sub.3                                                                      H                                                    --CH.sub.3      --CH.sub.3                                                                               H                                                    ______________________________________                                    

Still other compounds of the instant invention include the following compounds: ##STR5##

The novel compounds of the present invention are generally prepared by a process (illustrated in Scheme 1) comprising the treatment of an appropriate halogenated benzaldehyde with a suitably substituted phenol to provide the phenoxy benzaldehyde of the Formula II. This benzaldehyde is then reacted with a suitable dialkyl phosphite which provides the compound of Formula I upon saponification of the phosphonate moiety. ##STR6##

The starting materials of the process described above are commercially available or known in the literature.

The compounds of this invention form salts with various inorganic and organic acids and bases which are also within the scope of the invention. Such salts include ammonium salts, alkali metal salts like sodium and potassium salts, alkaline earth metal salts like the calcium and magnesium salts, salts with organic bases; e.g., dicyclohexylamine salts, N-methyl-D-glucamine, salts with amino acids like arginine, lysine, and the like.

The non-toxic, physiologically, acceptable salts are preferred, although other salts are also useful; e.g., in isolating or purifying the product.

The salts can be formed by conventional means such as by reacting the free acid forms of the product with one or more equivalents of the appropriate base in a solvent or medium in which the salt is insoluble, or in a solvent such as water which is then removed in vacuo or by freeze-drying or by exchanging the cations of an existing salt for another cation on a suitable ion exchange resin.

It will be further appreciated that the compounds of general Formula I in this invention may be derivatized at functional groups to provide prodrug derivatives which are capable of conversion back to the parent compounds in vivo. The concept of prodrug administration has been extensively reviewed (e.g. A. A. Sinkula in Annual Reports in Medicinal Chemistry, Vol. 10, R. V. Heinzelman, Ed., Academic Press, New York Lond, 1975, Ch. 31, pp. 306-326), H. Ferres, Drugs of Today, Vol. 19, 499-538 (1983) and J. Med. Chem., 18, 172 (1975).

Mode of Administration and Pharmaceutical Compositions.

Because of their ability to inhibit the enzymatic activity of the various forms of phospholipase C, the compounds of Formula I of the present invention can be used to reduce inflammation and relieve pain in diseases such as rheumatoid arthritis, emphysema, bronchial inflammation, osteoarthritis, spondylitis, lupus, psoriasis, acute respiratory distress syndrome, gout, rheumatic fever and the like. Furthermore the compounds can also be used to treat cancer, especially certain forms of cancer associated with phospholipase C, such as primary human breast carcinomas.

When the compounds of formula I are utilized in vivo, such compounds can be administered orally, topically, parentally, by inhalation spray or rectally in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers.

Accordingly, the present invention also provides pharmaceutical compositions comprising the compounds of formula I with a pharmaceutically acceptable carrier.

The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. In addition to the treatment of mammals, such as mice, rats, horses, dogs, cats, etc., the compounds of the invention are effective in the treatment of humans.

Pharmaceutical compositions of this invention comprise compounds of Formula I and pharmaceutical carders suitable for the route of administration. Standard methods for formulating pharmaceutical composition of this type may be found in Remington's Pharmaceutical Sciences, Mack Publishing Company, Easton, Pa.

The pharmaceutical compositions containing the active ingredient may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavoring agents, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparation.

Formulations for oral use include tablets which contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients. These excipients may be, for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate, granulating and disintegrating agents, for example, maize starch, or alginic acid; binding agents, for example, starch, gelatin or acacia, and lubricating agents, for example, magnesium stearate, stearic acid or talc. The tables may be uncoated or they be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl disterate may be employed.

Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example, peanut oil, liquid paraffin, or olive oil.

A typical tablet or capsule may contain the following:

    ______________________________________                                         Ingredient       Percent w/w                                                   ______________________________________                                         Lactose, spray-dried                                                                            40-99                                                         Magnesium stearate                                                                              1-2                                                           Cornstarch       10-20                                                         Active ingredient                                                                               0.001-20                                                      ______________________________________                                    

The pharmaceutical compositions of the invention may also be in the form of oil-in-water emulsions. The oily phase may be a vegetable oil, for example, olive oil or arachis oils, or a mineral oil, for example, liquid paraffin or mixtures of those. Suitable emulsifying agents may be naturally-occurring gums, for example, gum acacia or gum tragacanth, naturally-occurring phosphatides, for example, soybean lecithin; and esters including partial esters derived from fatty acids and hexitol anhydrides, for example, sorbitan mono-oleate, and condensation products of said partial esters with ethylene oxide, for example, polyoxyethylene sorbitan mono-oleate. The emulsions may also contain sweetening and flavoring agents.

Syrups and elixirs may be formulated with sweetening agents, for example, glycerol, sorbitol or sucrose. Such formulations may also contain a demulcent, a preservative and flavoring and coloring agents. The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleaginous suspension. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents which have been mentioned above.

Parenteral compositions are prepared in conventional suspension or solution forms, as emulsions or as solid forms for reconstruction. Suitable carders are water, saline, dextrose, Hank's solution, Ringer's solution, glycerol, and the like. Parenteral administration is usually by injection which may be subcutaneous, intramuscular or intravenous.

The sterile injectable prepartion may be sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent. Among the acceptable vehicles and solvents that may be x s employed are water, 1,3-butanediol. Ringer's solution and isotonic sodium chloride solution. In addition, sterile fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono- or diglycerides. Fatty acids such as oleic acid also find use in the preparation of injectables.

The compounds of formula I can also be administered in the form of suppositories for rectal administration of the drug. These compositions can be prepared by mixing the drug with a suitable non-irritating excipient which is solid at ordinary temperatures but liquid at the rectal temperature and while therefore melt in the rectum to release the drug, for example, cocoa butter and polyethylene glycols.

When the compounds of formula I are utilized in vivo, dosage levels on the order of from about 0.2 mg to about 300 mg, preferably from about 10 mg to about 100 mg, per kilogram of body weight per day are useful.

Aqueous suspensions usually contain the active materials in admixture with appropriate excipients. Such excipients are suspending agents, for example, sodium carboxymethylcellulose, methylcellulose, hydroxypropymethylcellulose, sodium alinate, polyvinylpyrolidone, gum tragacanth and gum acacia; dispersing or wetting agents which may be a naturally-occuring phosphatide, for example, lecithin; a condensation product of an alkylene oxide with a fatty oxide, for example, polyoxyethylene stearate; a condensation product of ethylene oxide with a long chain aliphatic alcohol, for example, heptadecaethyleneoxycetanol; a condensation product of ethylene oxide with a partial ester derived from fatty acids and a hexitol such as polyoxyethylene sorbitol monooleate; or a condensation product of ethylene oxide with a partial ester derived from fatty acids and hexitol anhydrides, for example, polyoxyethylene sorbitan monooleate. The aqueous suspensions may also contain one or more preservatives, for example, ethyl, n-propyl, or p-hydroxybenzoate; one or more coloring agents; one or more flavoring agents; and one or more sweetening agents such as sucrose or saccharin.

Oily suspension may be formulated by suspending the active ingredients in a vegetable oil, for example, arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oily suspension may contain a thickening agent, for example, beeswax, hard paraffin or cetyl alcohol. Sweetening agents such as those set forth above and flavoring agents may be added to provide a palatable oral preparation. These compositions may be preserved by the addition of an antioxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those already mentioned above. Additional excipients, for example, sweetening, flavoring and coloring agents, may also be present.

For topical administration, the pharmaceutical composition may be in the form of a salve, cream, ointment, spray, powder or the like. Standard pharmaceutical carriers for such compositions may be used. Preferably, compositions for topical administration will contain 0.05-5% of the active ingredient.

A typical cream formulation may contain the following:

    ______________________________________                                         Ingredient        Parts by Weight                                              ______________________________________                                         Water/glycol mixture                                                                             50-99                                                        (15% or more glycol)                                                           Fatty alcohol      1-20                                                        Non-ionic surfactant                                                                              0-10                                                        Mineral oil        0-10                                                        Typical pharmaceutical                                                                           0-5                                                          adjuvants                                                                      Active ingredient 0.05-5                                                       ______________________________________                                    

A typical ointment formulation may contain the following:

    ______________________________________                                         Ingredient      Parts by Weight                                                ______________________________________                                         White petrolatum                                                                               40-99                                                          Mineral oil     5-20                                                           Glycol solvent  1-15                                                           Surfactant      0-10                                                           Stabilizer      0-10                                                           Active Ingredient                                                                              0.05-5                                                         ______________________________________                                    

The compounds of this invention may be combined with other known anti-inflammatory/immunosuppressive agents such as steroids or non-steroidal anti-inflammatory agents (NSAID) in the pharmaceutical compositions and methods described herein.

Dosage levels of the order from 0.1 mg to 140 mg per kilogram of body weight per day are useful in the treatment of the above-indicated conditions (10 mg to 7 gms per patient per day). For example, inflammation is effectively treated and anti-pyretic and analgesic activity manifested by the administration from about 0.5 to 50 mg of the compound per kilogram of body weight per day (25 mg to 3.5 gms per patient per day). Preferably, a dosage of from about 2 mg to about 20 mg per kilogram of body weight per day is used to produce effective results (50 mg to 1 gm per patient per day).

Similarly with regard to treatment of certain forms of cancer, administration is in an amount between about 0.1 mg/kg of body weight to about 20 mg/kg of body weight per day, preferably of between 0.5 mg/kg of body weight to about 10 mg/kg of body weight per day.

The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. For example, a formulation intended for the oral administration of humans may contain from 5 mg to 5 gm of active agent compounded with an appropriate and convenient amount of carrier material which may vary from about 5 to 95 percent of the total composition. Dosage unit forms will generally contain between about 25 mg to about 500 mg of active ingredient.

It will be understood, however, that the specific dose level for any particular patient will normally be determined by the prescribing physician and will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the particular disease undergoing therapy.

EXPERIMENTAL PROCEDURES EXAMPLE 1 1-Hydroxy-1-(3-(3-chlorophenoxy)phenyl)methylphosphonic acid

Step A: 3-(3-Chlorophenoxy)benzaldehyde

A mixture of 3-bromobenzaldehyde (6.0g), 3-Chlorophenol (4.8g), sodium hydride (1.3 g of an 80% suspension in oil) and cuprous cloride (1 g) was heated under reflux in pyridine (125 ml) under an atmosphere of nitrogen gas for 16 hours. The mixture was cooled, diluted with water, acidified with hydrochloric acid and extracted with diethyl ether. The etheral extracts were dried (Na₂ SO₄), concentrated and purified by chromatography on silica gel eluting with ethyl acetate-petroleum ether (1:9) to give the title compound as a colourless oil.

Step B: Dimethyl 1-Hydroxy-1-(3-(3-chlorophenoxy)phenyl)methylphosphonate

The foregoing aldehyde (1.5 g) was stirred for 24 hours in a mixture of triethylamine (0.9 ml) and dimethyl phosphite (0.89 ml). The mixture was evaporated under reduced pressure and crystallised from ethyl acetate to give the tile compound as a white solid.

Step C: 1-Hydroxy-1-(3-(3-chlorophenoxy)phenyl)methylphosphonic acid

The phosphonate ester of part b) (0.5 g) was treated with trimethylsilyl bromide (0.96 ml) for 16 hours after which time the mixture was evaporated under reduced pressure and the residue dissolved in methanol (5 ml) for 10 minutes. The solution was concentrated and the residue dissolved in water and freeze dried to give the title compound as a white solid, ¹ H NMR (360 MHz, d₆ DMSO) δ4.70 (1H, d, J=14 Hz), 6.91-6.97 (2H, m), 7.02 (1H, t, J=2.2 Hz), 7.13 (1H, d, J=1.5 Hz), 7.17 (1H, d, J=6.2 Hz), 7.23 (1H, d, J=7.4 Hz), 7.32-7.40 (2H, m).

Examples 2-7 were prepared by the method of Example 1 using the appropriately substituted phenol.

EXAMPLE 2 1-Hydroxy-1-(3-phenoxyphenyl)methylphosphonic acid

¹ H NMR (360 MHz, D₂ O) δ4.93 (1H, d, J=12.8 Hz), 7.00 (1H, d, J=8.1 Hz), 7.08 (2H, d, J=7.8 Hz), 7.14 (1 H, d, J=1.9 Hz), 7.20 (1H, t, J=7.6 Hz), 7.25 (1H, d, J=7.6 Hz), 7.38-7.45 (3H, m).

EXAMPLE 3 1-Hydroxy-1-(3-(3,4-dichlorophenoxy)phenyl)methylphosphonic acid

¹ H NMR (360 MHz, d₆ DMSO) δ4.70 (1H, d, J=14.3 Hz), 6.94-7.01 (2H, m), 7.12 (1H, d, J=1.7 Hz), 7.23-7.25 (2H, m), 7.35 (1H, t, J=7.8 Hz), 7.61 (1H, d, J=8.9 Hz).

EXAMPLE 4 1-Hydroxy-1-(3-(4-chlorophenoxy)phenyl)methylphosphonic acid

¹ H NMR (360 MHz, d₆ DMSO) δ4.67 (1H, d, J=14.3 Hz), 6.88 (1H, d, J=7.0 Hz), 7.00-7.02 (2H, dd, J=2.1 and 8.9 Hz), 7.09 (1H, s) 7.19 (1H, d, J=7.0 Hz), 7.31 (1H, t, J=7.0 Hz), 7.39-7.42 (2H, dd, J=2.1 and 8.9 Hz).

EXAMPLE 5 1-Hydroxy-1-(3-(2-chlorophenoxy)phenyl)methylphosphonic acid

¹ H NMR (360 MHz, d₆ DMSO) δ4.68 (1H, d, J=14.3 Hz), 6.79 (1H, d, J=8.0 Hz), 7.03-7.06 (2H, m), 7.17-7.21 (2H, m), 7.27-7.36 (2H, m), 7.58 (1H, dd, J=8.0 and 1.6 Hz).

EXAMPLE 6 1-Hydroxy-1-(3-(4-methoxyphenoxy)phenyl)methylphosphonic acid

¹ H NMR (360 MHz, d₆ DMSO) δ3.74 (3H, s), 4.65 (1H, d, J=14.2 Hz), 6.76 (1H, d, J=7.8 Hz), 6.93-7.02 (5H, m), 7.09 (1H, d, J=7.8 Hz), 7.23 (1H, t, J=7.8 Hz).

EXAMPLE 7 1-Hydroxy-1-(3-(4-methylphenoxy)phenyl)methylphosphonic acid

¹ H NMR (360 MHz, d₆ DMSO) δ2.28 (3H, s), 4.65 (1H, d, J=14.2 Hz), 6.80 (1H, d, J=8 Hz), 6.90 (2H, d, J=9 Hz), 7.04 (1H, d, J=1.5 Hz), 7.12 (1H, d, J=8 Hz), 7.17 (2H, d, J=9 Hz), 7.27 (1H, t, J=8 Hz).

EXAMPLE 8 1-Hydroxy-1-(3-(4-hydroxyphenoxy)phenyl)methylphosphonic acid

Dimethyl 1-Hydroxy- 1-(3-(4-methoxyphenoxy)phenyl)-methylphosphonate was prepared by the method of Example 1a) and 1b) using 4-methoxyphenol. A solution of this compound (150 mg) in dry dichloromethane (10 ml) at -78° C. under an atmosphere of nitrogen was treated with boron tribromide (4 ml of a 1M solution in dichloromethane). The solution was allowed to warm to 20° C. then concentrated under reduced pressure. The residue was treated with trimethylsilyl bromide (1.2 ml) for 3 hours then concentrated and dissolved in methanol. After 10 minutes the solution was concentrated under reduced pressure. The residue was dissolved in water and freeze dried to give the title compound as a white solid, ¹ H NMR (360 MHz, D₂ O) δ4.93 (1H, d, J=12.6 Hz), 6.88-7.02 (5H, m), 7.07 (1H, d, J=1.8 Hz), 7.19 (1H, d, J=7.5 Hz), 7.37 (1H, t, J=7.5 Hz).

EXAMPLE 9 1-Hydroxy-1-(4-(3-chlorophenoxy)phenyl)methylphosphonic acid

Step A: 4-(3-Chlorophenoxy)benzaldehyde

3-Chlorophenol (1.9 g) was stirred with 4-fluoro-benzaldehyde (1.8 g) and sodium hydride (0.46 g of an 80% suspension in oil) in dimethylformamide (50 ml) at 110° C. under an atmosphere of nitrogen for 16 hours. The solution was diluted with water and extracted with diethyl ether. The ethereal extract was dried (Na₂ SO₄), concentrated and purified by chromatography on silica gel eluting with ethyl acetate-petroleum ether (1:9) to give the title compound as a colourless oil.

Step B: 1-Hydroxy-1-(4-(3-chlorophenoxy)phenyl)methylphosphonic acid

This was prepared from 4-(3-Chlorophenoxy)benzaldehyde using the methods of Example 1b) and 1c). ¹ H NMR (360 MHz, d₆ DMSO) δ4.69 (1H, d, J=13.6 Hz), 6.92-7.02 (4H, m), 7.15-7.18 (1H, m), 7.37-7.46 (3H, m).

EXAMPLE 10 1-Hydroxy-1-(4-(3-ethylphenoxy)phenyl)methylphosphonic acid

Prepared by the method of Example 9 using 3-ethylphenol. ¹ H NMR (360 MHz, d₄ MeOH/CDCl₃) δ1.21 (3H, t, J=7.6 Hz), 2.61 (2H, q, J=7.6 Hz), 4.90 (1 H, d, J=11.7 Hz), 6.78 (1H, dd, J=2.1 and 8.0 Hz), 6.84 (1H, s), 6.94 (1H, d, J=7.0 Hz), 6.97 (2H, d, J=8.6 Hz), 7.22 (1H, t, J=7.8 Hz), 7.46 (2H, dd, J=1.8 and 8.6 Hz).

EXAMPLE 11 1-Hydroxy-1-(4-(3-methoxyphenoxy)phenyl)methylphosphonic acid

Prepared by the method of Example 9 using 3-methoxyphenol and convened to the bis-cyclohexylammonium salt by treating with cyclohexylamine in a mixture of methanol and ethylacetate, then filtering and drying. ¹ H NMR (360 MHz, D₂ O) δ1.14-1.40 (10H, m), 1.63-1.67 (2H, m), 1.77-1.81 (4H, m), 1.96-1.99 (4H, m), 3.09-3.16 (1H, m), 3.80 (3H, s), 4.71 (1H, d, J=11.4 Hz), 6.71-6.73 (2H, m), 6.78-6.81 (1H, m), 7.06 (2H, d, J=8.6 Hz), 7.32-7.37 (1H, m), 7.48 (2H, d, J=8.6 Hz).

EXAMPLE 12 Assay Protocol for Evaluating Inhibition of Phospholipase Cγ

General. Competent DH5α cells (subcloning efficiency) were obtained from GIBCO/BRL (Gaithersburg, Md.). Competent BL21(DE3) cells were purchased from Novagen (Madison, Wis.). PCR mutagenesis was carried out according to literature protocol (Higuchi, 1990). The general cloning vector, pBSII(S/K)+, was from Stratagene (La Jolla, Calif.). pT5T was constructed as described (Eisenberg et al., 1990). DNA sequencing was performed at each sequence modification on the relevant portion of the gene using the dideoxy chain termination method (Sanger et al., 1977) to verify the change to the wild type cDNA. Standard DNA manipulations were carded out as described (Sambrook et al., 1989).

Oligonucleotides. Synthetic deoxyribonucleotides were obtained from Midland Certified Reagent Co. (Midland, Tex.). The sequences of the oligonucleotides are (5' to 3'):

    __________________________________________________________________________     01                                                                               CCC--GGG--CAT--ATG--GAT--CCA--TTG--GAG--GAT--GAT--TAA--                        ATG--GCG--GGC--GCC--GCG--TCC (SEQ. ID. NO.: 4)                               02                                                                               CTG--CTT--CCG--GAG--CCA--CCT--CTC (SEQ. ID. NO.: 5)                          03                                                                               TC--GCC--ATT--CGT--CCT--GAG--GGC (SEQ. ID. NO.: 6)                           04                                                                               GG--GCC--CAA--GCT--TCT--AGA--CTA--AAA--TTC--TTC--GAG--                         GCG--GTT--GTC--TCC--ATT--GAC--CCG--AGT--TCG--TCG                               (SEQ. ID. NO.: 7)                                                            05                                                                               G--ATG--ATG--GAG--CGG--CGG--AAG--AAG--ATC--G                                   (SEQ. ID. NO.: 8)                                                            06                                                                               C--GAT--CTT--CTT--CCG--CCG--CTC--CAT--CAT--C                                   (SEQ. ID. NO.: 9)                                                            __________________________________________________________________________

Subcloning of the PLCγ Coding Sequence. Rat brain cDNA is synthesized using rat brain poly(A)RNA as template by literature protocol (Sanbrook, J. et al., Molecular Cloning: A Laboratry Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.). From the published cDNA sequence of rat brain PLCγ₁ (Suh, P.-G., Ryu, S. H., Moon, K. H., Suh, H. W., & Rhee, S. G. (1988) Proc. Natl. Acad. Sci. USA 85, 5419-5423), PCR primers, one which contains a BamHI restriction site upstream of the sequence complementary to the 5' end of the PLCγ₁ gene (primer 01), and the other one which contains a HindIII site downsteam of the 3' end of the PLCγ gene (primer 04), were synthesized. Carrying out the PCR using these primers (01 and 04) with the above mentioned rat brain cDNA as template, a DNA fragment with the entire rat brain PLCγ₁ coding sequence, flanked by a 5' BamHI site and a 3' HindIII site, is generated. This BamHI-HindIII fragment containing the coding sequence of PLCγ was subcloned into pBSII(S/K)+, generating pPLC1. The rest of the manipulations were accomplished using PCR to generate the appropriate DNA fragment. The 5' end of the PLC.sub.γ1 gene was altered to include a new BamHI site and a sequence that would eventually translationally couple the expression of PLCγ₁ to the φ10 gene of the pT5T vector as described by Eisenberg, S. P., Evans, R. J., Arend, W. P., Verderber, E., Brewer, M. T., Hannum, C. H., & Thompson, R. C. (1990) Nature(London) 343, 341-346.

Primers 01 and 02 were used to generate a 508 bp fragment (from template DNA pPLC1 ) containing a 5' BamHI site and 3' EcoRI site. This new restriction fragment was substituted for the analogous fragment in pPLC1 to produce pPLC2.

PCR-mediated mutagenesis with template pPLC2 and with primers 03-05 to generate one mutant fragment and primers 04-06 to generate the second mutant fragment was used to restructure the 3' end, to add DNA sequence encoding the epitope tag Glu-Glu-Phe (which is recognized by the monoclonal antibody YL1/2) (Kilmartin, J. V., Wright, B., & Milstein, C. (1982) J. Cell. Biol. 93,576-582), and to change the tandem AGG-AGG codons to CGG-CGG at amino acid positions 944-945 and 1279-1280. Tandem AGG codons are associated with poor protein expression in E. coli (Bonekamp, F., & Jensen, K. (1988) Nucl. Acids Res. 17, 3013-3024).

Using the isolated mutant fragments from each of these PCRs together as template, the final PCR was carried out using primers 03-06 which yielded, after restriction enzyme digestion, a SphI and HindIII fragment which was used to replace the analogous fragment in pPLC2. The resulting plasmid, pPLC3, contained the coding sequence of the PLCγ₁ gene on a BamHI-HindIII fragment with both the sequence encoding the Glu-Glu-Phe tag at the 3' end as well as the changed AGG codons. FIG. 3 shows the final cDNA sequence encoding the enzyme and its epitope tag. (SEQ.ID.NO.: 3) Finally, the BamHI-HindIII fragment from pPLC3 was transferred into the BamHI-HindIII site of pT5T, generating pT5T-PLC4. This construct was used to produce PLCγ₁ (containing the Glu-Glu-Phe epitope tag at the C-terminus) translationally coupled to the expression of p10 protein in the pT5T vector.

Expression and Purification of PLCγ₁. To express PLCγ₁ the plasmid pT5T-PLC4 was transformed into E. coli BL21 (DE3). The transformed cells were grown in LB media containing ampicillin (100 gg/ml) and tetracycline (12.5 μ/ml) at 20° C. until the optical density of the cultures at 550 nm was equal to 0.8. This transformed bacterial cell has been deposited with the ATCC and has been assigned the number ATCC 69421. Expression of PLCγ₁ was then induced by addition of isopropyl β-D-thiogalactopyranoside (0.5 mM final concentration) to the cultures. After growing for another 6 hours the cells were harvested and PLCγ₁ was purified as described below. PLCγ was isolated from E. coli by resuspending a cell pellet in standard buffer, 50 mM Tris-Cl pH 8.0, 2 mM MgCl₂, 10 mM CaCl₂, 1 mM EGTA, 5 mM DTT, 5 mM streptomycin sulfate, 1 mM PMSF, 2 μ/ml leupeptin, 2 μ/ml antipain, 10 μ/ml aprotinin (approximately 5 g wet packed cells/10 ml buffer). The resuspended cells were broken by sonication and the cell debris pelleted by centrifugation at 30,000×g at 4° C. for 30 minutes. The soluble fraction was applied at a flow rate of approximately 0.5 ml/min to a 2 ml column of the monoclonal antibody YL1/2(4mg antibody/ml resin) coupled to cyanogen bromide activated Sepharose. The YL1/2 Sepharose column, which binds the epitope tag Glu-Glu-Phe had previously been equilibrated with standard buffer. After loading the protein onto the column, the column was washed with standard buffer (100 mls) PLCγ was eluted with 3×5 ml 5 mM Asp-Phe dipeptide (Sigma) in standard buffer. The column was regenerated by washing with phosphate buffered saline (PBS)+2M NaCl and then stored in PBS+0.02% NaN₃ (wt./vol). The PLCγ₁ was obtained in>80% purity and in a 0.05 to 0.5% yield based on the total starting soluble E. coli protein. In some cases the the PLCγ₁ was futher purified. This is not necessary for routine drug screening. To further purify the PLCγ₁ the protein eluted from the YL1/2 column was chromatographed by HPLC on a MonoQ HR 10-10 column (Pharmacia) where buffer A was standard buffer and buffer B was standard buffer+1M KCl. The column was run at 1 ml/min and the gradient was 0-30% B in 40 min., 30-50% B in 50 min., 50-100% "B" in 70 min. PLCγ₁ eluted at approximately 25-30% B.

Assay of purified PLCγ₁ activitiy. Activity of the purified PLCγ₁ was assayed at 30° C. Reactions were never allowed to proceed to more than 10% completion based on the limiting substrate. A typical reaction contained the following: 50 mM HEPES pH7.5, 0.1% Deoxycholate, 3 mM CaCl₂, 1 mM EGTA, 0.1 mM DTT with phosphatidyl inositol (1-1000 μM) (PI) and 0.02 uCi [³ H]-phosphatidyl inositol (PI) as substrate. The phospholipid components were dried under a gentle stream of nitrogen and resuspended in assay buffer. The substrate mix is then vortexed and sonicated (10 sec. with probe sonicator) to disperse the lipid and form micelles. After thermally preequilibrating the assay mixture in the absence of enzyme, the reaction was initiated by adding PLCγ₁. Reactions containing 0.2 ml aliquots were terminated by addition of 1/4 volume 1N HCl, 5 mM EGTA and transferred to an ice bath. The quenched reactions are then filtered through a Q sepharose (Pharmacia) column. To prepare the Q sepharose column 1 ml of Q Sepharose slurry is added to a disposable plastic column. The resin is equilibrated by passing through 20 ml of 10 mM NH₄ H₂ PO₄, pH 3.5. The quenched reaction, typically 200 μl, is applied to the column and 3 ml of 10 mM NH₄ H₂ PO₄, pH 3.5 is added, the flow through from this step is collected in a scintillation vial, mixed with 10 ml of scintillation fluid and counted in a Beckman LS3801 scintillation counter.

Assay of inhibitory activity of the compounds of the invention. The inhibitory activity of the compounds of formula I against PLCγ₁ was assessed by including known concentrations of the compound of formula I in the assay mixture described above prior to the addition of the enzyme. The relative inhibitory concentrations calculated from the assay are shown in Tables 1 and 2.

                  TABLE 1                                                          ______________________________________                                          ##STR7##                                                                      Example No. R.sup.3 R.sup.4 R.sup.5                                                                               IC.sub.50 (μM)                           ______________________________________                                         1           H       Cl      H      10                                          2           H       H       H      190                                         3           H       Cl      Cl     56                                          4           H       H       Cl     36                                          5           Cl      H       H      17                                          6           H       H       OCH.sub.3                                                                              7                                          7           H       H       CH.sub.3                                                                              13                                          8           H       H       OH      3                                          ______________________________________                                    

                  TABLE 2                                                          ______________________________________                                          ##STR8##                                                                      Example No.                                                                               R.sup.3 R.sup.4     R.sup.5                                                                            IC.sub.50 (μM)                           ______________________________________                                          9         H       Cl          H   5                                           10         H       CH.sub.2 CH.sub.3                                                                          H   37                                          11         H       OCH.sub.3   H   8                                                      H       H           H   >300                                        ______________________________________                                    

EXAMPLE 13 Assay Protocol for Evaluating Inhibition of Phospholipase C-β and δ

Purification of Phospholipase C-β and δ from Bovine Brain

PLC-β are obtained as described by S. G. Rhee et al., Meth. Enzym., 197:502-511 (1991). Specifically PLC-δ is purified from the cytosolic fraction of bovine brains, while PLC-β is mainly obtained from the particulate fraction. However, since the particulate and cytosolic forms of PLC-β are identical with respect to amino acid sequence, PLC-β-containing fractions pooled during the purification of the cytosolic PLC-δ are combined with the PLC-β fraction from the particulate fraction. A total of 36 bovine brains are used for the purification. Twelve brains are processed at one time.

Step 1: Separation of Cytosolic and Particulate Fractions. Twelve bovine brains are freshly obtained from a local slaughterhouse, and the cerebra (3.3 kg) are homogenized in a Waring blender with 6.6 liters of buffer containing 20 mM Tris-HCl, pH 7.4, 5 mM EGTA, 2 mM phenylmethysulfonyl fluoride (PMSF), and 0.1 mM DTT. The homogenate is centrifuged for 30 min at 13,000 g at 4°. Both the precipitate and supernatant are saved for Steps 2 and 3, respectively.

Step 2: Preparation of Extracts from Particulate Fractions.

The precipitate from Step 1 is resuspended in the same homogenization buffer (6.6 liters) and homogenized again to ensure complete breakage of cells. The homogenate is centrifuged for 30 min. at 13,000 g. The washed pellet is suspended in 2M KCl in homogenization buffer and stirred for 2 hr at 4°. The suspension is then centrifuged for 90 min at 13,000 g. The supernatant is brought to 60% (NH₄)₂ SO₄ saturation by adding solid salt. This suspension is centrifuged for 30 min at 13,000 g, and the pellet is suspended in 500 ml of homogenization buffer; the suspension is dialyzed overnight against the homogenization buffer. Dialyzed solution is centrifuged for 30 min at 13,000 g to remove insoluble particles, and the supernatant, which is still very turbid, is kept at -20° to be combined with the dialyzed solutions from the two other identical preparations.

Step 3: Preparation of Cytosolic Extracts. The supernatant from Step 1 is adjusted to pH 4.8 with 1M acetic acid. After 30 min at 4°, precipitates are collected by centrifugation and dissolved in 1 liter of homogenization buffer. Insoluble materials are pelleted by centrifuging for 30 min at 13,000 g, and the turbid supernatant is removed for Step 4.

Step 4: Ion-Exchange Chromatography on DEAE-Cellulose.

The supernatant from Step 3 is applied to a DE-52 DEAE-cellulose (Whatman Biosystems, Maidstone, UK) column (8×40 cm), which has been equilibrated with 20 mM Tris-HCl, pH 7.6, 1 mM EGTA, 0.1 mM DTT. The column is eluted with a 6-liter linear KCl gradient from 0 to 225 mM KCl in 50 mM Tris-HCl, pH 7.6, 1 mM EGTA, and 0.1 mM DTT. Three PLC activity peaks are eluted and the peak fractions are pooled separately. The first peak, which contains PLC-δ, is further purified immediately in the next step. The second peak fractions containing PLC-β are concentrated to about 100 ml and combined with the extracts of particulate fractions from Step 2. The third peak fractions containing PLC-γ are discarded.

Purification of PLC-δ

Step 5: Heparin-Agarose Chromatography of PLC-δ. The PLC-β fractions pooled from the previous step (750 ml) are directly applied to a heparin-agarose column (5×15 cm) equilibrated with 20 mM HEPES, pH 7.0, 0.1 mM DTT, and 1 mM EGTA. The column is eluted with a 1.8-liter linear gradient of NaCl from 100 to 700 mM NaCl in equilibration buffer. The peak fractions (240 ml) are pooled, concentrated to approximately 10 ml in an Amicon (Danvers, Mass.) filtration apparatus, and stored frozen to be combined with concentrated fractions of PLC-δ from two other identical preparations.

Step 6: Reversed-Phase Chromatography of PLC-δ, on TSK Phenyl-5-PW. Solid KCl is added to the combined concentrated fractions (35 ml) from Step 5 to give a final concentration of 3M, and the mixtures are centrifuged to remove denatured proteins. The supernatants are applied at a flow rate of 5.0 ml/min to a high-performance liquid chromatography (HPLC) preparative TSK phenyl-5-PW column (21.5×150 mm; Bio-Rad, Richmond, Calif.) equilibrated with 20 mM HEPES, pH 7.0, 3M KCl, 1 mM EGTA, and 0.1 mM DTT. Elution is continued at 5.0 ml/min with a decreasing KCl gradient from 3 to 1.2M KCl for 10 min and with a decreasing KCl gradient from 1.2 to 0M KCl for 20 min. Fractions (25 ml) containing PLC activity are pooled and washed in an Amicon filtration apparatus with 20 mM MOPS buffer, pH 5.7, 0.1 mM DTT, 1 mM EGTA, and finally concentrated to about 10 ml.

Step 7: Ion-Exchange Chromatography of PLC-δ on a Mono S Column. The washed protein solution (˜10 ml) from Step 6 is applied at a flow rate of 1.0 ml/min to a Mono S column (70×6 mm, Pharmacia, Piscataway, N.J.) equilibrated with 20 mM MOPS, pH 5.7, 0.1 mM DTT, and 1 mM EGTA. Elution is continued at 1.0 ml/min with a NaCl gradient from 0 to 300 mM NaCl for 20 min and from 300 mM to 1M for 10 min. Peak fractions (1.2 ml) are collected manually, diluted with 2 ml of 20 mM HEPES (ph 7.0), concentrated in a Centricon microconcentrator (Amicon) to approximately 0.5 ml, separated into aliquots, and stored at -20°. A total of 0.3-0.6 mg of homogeneous PLC-δ is obtained, with a yield of 2-4%.

Purification of PLC-β

Step 8: Ion-Exchange Chromatography of PLC-β on DEAE-Cellulose. Because of turbidity, the combined protein solution from Steps 2 and 3 cannot be chromatographed on a DEAE-cellulose column directly. Therefore, two stages of DEAE-cellulose chromatography, a batch procedure followed by a column step, are employed. In the batch step, all of the combined proteins are absorbed on 2 liters of DEAE-cellulose equilibrated with 20 mM Tris-HCl, pH 7.6, containing 5 mM EGTA and 0.1 mM DTT. The DEAE-cellulose slurry is stirred and then collected in a 4-liter sintered glass (coarse) filter funnel. The DEAE-cellulose is washed with the equilibration buffer until it is free of turbid lipid materials and unbound protein. For the column procedure, the washed DEAE-cellulose is removed from the filter funnel, mixed with the equilibration buffer, and poured onto a column already containing a 10 cm high bed of equilibrated DEAE-cellulose (final dimension, 8×45 cm). The column is eluted at a flow rate of 8 ml/min with an 8-liter linear gradient from 0 to 300 mM KCl buffer containing 50 mM Tris-HCl, pH 7.6, 1 mM EGTA, and 0.1 mM DTT. The activity peak is eluted at a KCl concentration of 110 mM. The peak fractions (600 ml) are pooled.

Step 9: Heparin-Agarose Chromatography of PLC-β. The pooled fraction from Step 8 (600 ml) is applied to a heparin-agarose column (5×25 cm) equilibrated with 20 mM HEPES, pH 7.0, 100 mM NaCl, 0.1 mM DTT, and 1 mM EGTA. The column is eluted with a linear gradient from 100 to 500 mM NaCl in 1.5 liters of equilibrium buffer. Peak fractions (310 ml) are pooled and concentrated on an Amicon filter to 27 ml.

Step 10: Reversed-Phase Chromatography of PLC-β on TSK Phenyl-5-PW. Solid KCl is added to the concentrated fractions from Step 9 to give a concentration of 3M, and the mixtures are centrifuged to remove denatured proteins. The supernatants are applied at a flow rate of 5 ml/min to an HPLC preparative phenyl-5-PW column (150×215 mm) equilibrated with 20 mM HEPES, pH 7.0, 3M KCl, 1 mM EGTA, and 0.1 mM DTT. Elution is continued at 5 ml/min with a decreasing KCl gradient from 3 to 1.2M for 15 min and with a decreasing gradient from 1.2 to 0M for 20 min. Then the column is washed with a KCl-free buffer. Fractions containing each of the two peaks of PLC activity (15 ml for fraction Ml and 13 ml for fraction M2) are collected separately. The pooled solutions are washed with a KCl-free 20 mM HEPES, pH 7.0, and are concentrated to 5 ml in an Amicon filter concentrating procedure. Analysis on SDS-polyacrylamide gels indicates that fractions M1 and M2 contain 150-kDa (PLC-β1) and 140-kDa (PLC-β2) forms of PLC, respectively. The two forms are immunologically indistinguishable. Whether PLC-β2 is a proteolytic fragment of PLC-β1 or a product of alternately spliced mRNA is not known. About 15 mg of PLC-β1 and 8 mg of PLC-β2 are obtained.

Assay of inhibitory activity of the compounds of the invention. The inhibitory activity of the compounds of formula I against PLCβ was assessed by including known concentrations of the compound of formula I in an assay mixture similar to the assay mixture described in Example 12, but substituting PLCβ obtained as described above for PLCγ of Example 12, prior to the addition of the enzyme. The relative inhibitory concentrations calculated from the assay are shown in Tables 3 and 4.

                  TABLE 3                                                          ______________________________________                                          ##STR9##                                                                      Example No. R.sup.3 R.sup.4 R.sup.5                                                                               IC.sub.50 (μM)                           ______________________________________                                         1           H       Cl      H      24                                          2           H       H       H      >300                                        3           H       Cl      Cl     110                                         4           H       H       Cl     65                                          5           Cl      H       H      38                                          6           H       H       OCH.sub.3                                                                             717                                         7           H       H       CH.sub.3                                                                              31                                          8           H       H       OH      7                                          ______________________________________                                    

                  TABLE 4                                                          ______________________________________                                          ##STR10##                                                                     Example No.                                                                               R.sup.3 R.sup.4     R.sup.5                                                                            IC.sub.50 (μM)                           ______________________________________                                          9         H       Cl          H    9                                          10         H       CH.sub.2 CH.sub.3                                                                          H   74                                          11         H       OCH.sub.3   H   11                                                     H       H           H   >300                                        ______________________________________                                    

The inhibitory activity of the compounds of formula I against PLCδ is assessed by including known concentrations of the compound of formula I in an assay mixture similar to the assay mixture described in Example 12, but substituting PLCδ obtained as described above for PLCγ of Example 12, prior to the addition of the enzyme.

    __________________________________________________________________________     SEQUENCE LISTING                                                               (1) GENERAL INFORMATION:                                                       (iii) NUMBER OF SEQUENCES: 9                                                   (2) INFORMATION FOR SEQ ID NO:1:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 3870 base pairs                                                    (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                        ATGGCGGGCGCCGCGTCCCCCTGCGCCAACGGCTGCGGGCCCAGCGCGCCCTCCGAAGCG60                 GAGGTGCTGCACCTCTGCCGCAGCCTCGAGGTGGGCACCGTCATGACTTTGTTCTACTCC120                AAGAAGTCGCAGCGGCCAGAACGGAAGACCTTCCAGGTCAA GTTGGAGACGCGCCAGATC180               ACATGGAGCCGCGGTGCGGACAAAATCGAGGGGTCCATCGATATCCGAGAAATCAAGGAG240                ATCCGCCCAGGGAAGACTTCCCGGGACTTTGACCGCTACCAAGAAGACCCTGCCTTCCGG300                CCAGATCAGTCACACT GTTTTGTCATCCTCTATGGAATGGAATTCCGCCTGAAGACCCTG360               AGCCTGCAAGCCACATCTGAGGATGAAGTGAACATGTGGATCAAGGGCTTAACTTGGCTC420                ATGGAAGATACGCTGCAGGCGGCCACACCCCTGCAAATTGAGAGATGGCTCCGGAAGCAG 480               TTCTACTCAGTGGATCGTAACCGAGAGGATCGTATATCAGCCAAGGACCTGAAGAACATG540                CTGTCACAGGTCAACTACCGGGTCCCCAACATGCGCTTCCTCCGAGAGCGGCTGACGGAC600                TTTGAACAGCGCAGCGGGGACATCACCTATGGGC AGTTTGCTCAGCTTTACCGCAGCCTC660               ATGTACAGCGCCCAGAAGACGATGGACCTTCCGTTCTTGGAAACCAACACTTTGAGGACT720                GGAGAGCGGCCAGAGCTTTGCCAGGTGTCCCTTTCTGAGTTCCAGCAGTTCCTTCTTGAG780                TACCAGGGG GAGCTGTGGGCTGTCGACCGGCTTCAGGTGCAGGAATTTATGCTCAGCTTC840               CTTCGAGACCCCTTGCGAGAGATTGAGGAGCCATACTTCTTCTTGGATGAGCTTGTCACC900                TTTCTGTTCTCCAAAGAGAACAGTGTGTGGAACTCACAGCTGGATGCCGTGT GCCCAGAA960               ACCATGAACAACCCACTGTCTCACTATTGGATCTCTTCCTCGCATAATACGTATCTGACT1020               GGGGACCAGTTCTCCAGCGAGTCCTCCCTGGAAGCCTACGCTCGCTGCCTGAGGATGGGC1080               TGTCGCTGCATCGAGTTGGACTGCTGG GATGGGCCAGATGGGATGCCAGTCATTTACCAT1140              GGGCACACCCTCACCACCAAGATTAAGTTCTCAGATGTCCTGCACACCATCAAGGAGCAC1200               GCGTTCGTAGCCTCAGAGTACCCTGTCATCCTGTCCATCGAGGACCACTGCAGCATTGCC1260               C AGCAGAGGAACATGGCCCAGCACTTCAGGAAGGTGCTCGGTGACACGCTCCTCACCAAG1320              CCCGTGGACATTGCCGCTGATGGGCTCCCTTCTCCCAACCAGCTCAAGAGGAAGATCCTG1380               ATTAAGCATAAGAAGCTGGCTGAGGGCAGTGCCTATGAGGAGGTG CCTACCTCTGTGATG1440              TACTCTGAGAATGACATCAGTAACTCCATCAAGAATGGTATCCTCTACTTGGAGGACCCC1500               GTGAATCATGAGTGGTACCCCCACTACTTTGTTCTGACTAGCAGCAAGATCTACTACTCT1560               GAGGAGACCAGCAGTGACCA GGGAAATGAGGATGAAGAGGAGCCGAAGGAGGCCAGTGGC1620              AGCACAGAGCTGCACTCGAGCGAGAAGTGGTTCCACGGGAAGCTCGGGGCTGGGCGCGAC1680               GGGCGGCACATTGCTGAGCGCCTGCTCACCGAGTACTGCATAGAGACTGGGGCTCCCGAT1 740              GGCTCCTTCCTAGTGCGAGAAAGTGAGACCTTCGTGGGGGACTACACGCTGTCTTTTTGG1800               CGGAATGGGAAAGTCCAGCACTGCCGTATCCACTCCCGGCAGGATGCTGGGACTCCTAAG1860               TTCTTCTTGACAGATAACCTTGTCTTTGACTCTCTCTA TGACCTCATCACACATTATCAG1920              CAAGTGCCCCTGCGCTGCAATGAGTTTGAGATGCGCCTTTCAGAGCCTGTTCCACAGACG1980               AATGCCCATGAGAGCAAAGAGTGGTACCACGCAAGCCTGACTAGAGCTCAGGCTGAACAC2040               ATGCTGATGCGA GTACCCCGTGATGGGGCCTTCCTGGTGCGGAAGCGCAACGAGCCCAAC2100              TCCTATGCCATCTCTTTCCGGGCTGAGGGAAAGATCAAGCACTGCCGAGTACAGCAGGAA2160               GGCCAGACTGTGATGCTGGGGAACTCTGAGTTTGACAGCCTGGTCGACCTCATCAG CTAC2220              TATGAGAAGCATCCCCTGTACCGCAAAATGAAACTGCGCTACCCCATCAACGAGGAGGCG2280               CTGGAGAAGATTGGGACAGCTGAACCCGATTATGGGGCACTGTATGAGGGCCGCAACCCT2340               GGTTTCTATGTGGAGGCCAACCCTATGCCA ACTTTCAAGTGTGCAGTAAAAGCTCTCTTC2400              GACTACAAGGCCCAGAGAGAGGATGAGCTGACTTTTACCAAGAGCGCCATCATCCAGAAT2460               GTGGAAAAGCAAGATGGTGGCTGGTGGCGTGGGGACTATGGTGGGAAGAAGCAGCTGTGG2520               TTCCC CTCAAACTATGTGGAAGAGATGATCAATCCAGCAATCCTAGAGCCGGAGAGGGAG2580              CATCTGGATGAGAACAGCCCACTGGGGGACTTGCTGCGAGGGGTCTTAGATGTGCCAGCC2640               TGCCAGATCGCCATTCGTCCTGAGGGCAAAAACAACCGGCTCTTCGTCT TCTCCATCAGC2700              ATGCCGTCAGTGGCTCAGTGGTCCCTAGACGTTGCCGCTGACTCACAGGAGGAGTTGCAG2760               GACTGGGTGAAAAAGATCCGTGAAGTTGCCCAGACTGCAGATGCCAGGCTTACTGAGGGG2820               AAGATGATGGAGCGGCGGAAGAA GATCGCCTTGGAGCTCTCCGAGCTCGTGGTCTACTGC2880              CGGCCTGTTCCCTTTGACGAAGAGAAGATTGGCACAGAACGCGCTTGTTACCGGGACATG2940               TCCTCCTTTCCGGAAACCAAGGCTGAGAAGTATGTGAACAAGGCCAAAGGCAAGAAGTTC3000               CTCCAGTACAACCGGCTGCAGCTCTCTCGCATCTACCCTAAGGGTCAGAGGCTGGACTCC3060               TCCAATTATGACCCTCTGCCCATGTGGATCTGTGGCAGCCAGCTTGTAGCTCTCAATTTT3120               CAGACCCCAGACAAGCCTATGCAGATGAACCAGGCCCTCTT CATGGCTGGTGGACACTGT3180              GGCTATGTGCTGCAGCCAAGCACCATGAGAGATGAAGCCTTTGACCCCTTTGATAAGAGC3240               AGTCTCCGAGGTCTGGAGCCCTGTGTCATTTGCATTGAGGTGCTGGGGGCCAGGCATCTG3300               CCGAAGAATGGCCGGG GTATTGTGTGTCCTTTCGTGGAGATTGAAGTGGCTGGGGCAGAG3360              TACGACAGCACCAAGCAGAAGACAGAGTTTGTAGTGGACAATGGACTGAACCCTGTGTGG3420               CCTGCAAAGCCCTTCCACTTCCAGATCAGTAACCCAGAGTTTGCCTTTCTGCGCTTTGTG 3480              GTGTATGAGGAAGACATGTTTAGTGACCAGAACTTCTTGGCTCAGGCTACTTTCCCAGTA3540               AAAGGCCTGAAGACAGGATACAGAGCAGTGCCTTTGAAGAACAACTACAGTGAAGACCTG3600               GAGTTGGCCTCCCTGCTCATCAAGATTGACATTT TCCCTGCTAAGGAGAATGGTGACCTC3660              AGCCCTTTCAGTGGTACATCCCTAAGGGAACGGGCCTCAGATGCCTCCAGCCAGCTGTTC3720               CATGTCCGGGCCCGGGAAGGGTCCTTTGAAGCCAGATACCAGCAGCCATTTGAAGACTTC3780               CGCATCTCG CAGGAGCATCTCGCAGACCATTTTGACAGTCGGGAACGAAGGGCCCCAAGA3840              AGGACTCGGGTCAATGGAGACAACCGCCTC3870                                             (2) INFORMATION FOR SEQ ID NO:2:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 1290 amino acids                                                   ( B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                        MetAlaGlyAlaAlaSerProCysAlaAsnGlyCysGlyProSerAla                               1510 15                                                                        ProSerGluAlaGluValLeuHisLeuCysArgSerLeuGluValGly                               202530                                                                         ThrValMetThrLeuPheTyrSerLysLysSerGl nArgProGluArg                              354045                                                                         LysThrPheGlnValLysLeuGluThrArgGlnIleThrTrpSerArg                               50556 0                                                                        GlyAlaAspLysIleGluGlySerIleAspIleArgGluIleLysGlu                               65707580                                                                       IleArgProGlyLysThrSerArgAspPheAspArg TyrGlnGluAsp                              859095                                                                         ProAlaPheArgProAspGlnSerHisCysPheValIleLeuTyrGly                               100105 110                                                                     MetGluPheArgLeuLysThrLeuSerLeuGlnAlaThrSerGluAsp                               115120125                                                                      GluValAsnMetTrpIleLysGlyLeuThrTrp LeuMetGluAspThr                              130135140                                                                      LeuGlnAlaAlaThrProLeuGlnIleGluArgTrpLeuArgLysGln                               145150155 160                                                                  PheTyrSerValAspArgAsnArgGluAspArgIleSerAlaLysAsp                               165170175                                                                      LeuLysAsnMetLeuSerGlnValAsn TyrArgValProAsnMetArg                              180185190                                                                      PheLeuArgGluArgLeuThrAspPheGluGlnArgSerGlyAspIle                               1952 00205                                                                     ThrTyrGlyGlnPheAlaGlnLeuTyrArgSerLeuMetTyrSerAla                               210215220                                                                      GlnLysThrMetAspLeuProPheLeuGluTh rAsnThrLeuArgThr                              225230235240                                                                   GlyGluArgProGluLeuCysGlnValSerLeuSerGluPheGlnGln                               245 250255                                                                     PheLeuLeuGluTyrGlnGlyGluLeuTrpAlaValAspArgLeuGln                               260265270                                                                      ValGlnGluPheMetLeuS erPheLeuArgAspProLeuArgGluIle                              275280285                                                                      GluGluProTyrPhePheLeuAspGluLeuValThrPheLeuPheSer                               290 295300                                                                     LysGluAsnSerValTrpAsnSerGlnLeuAspAlaValCysProGlu                               305310315320                                                                   ThrMetAsnAsnProLeu SerHisTyrTrpIleSerSerSerHisAsn                              325330335                                                                      ThrTyrLeuThrGlyAspGlnPheSerSerGluSerSerLeuGluAla                               34 0345350                                                                     TyrAlaArgCysLeuArgMetGlyCysArgCysIleGluLeuAspCys                               355360365                                                                      TrpAspGlyProAsp GlyMetProValIleTyrHisGlyHisThrLeu                              370375380                                                                      ThrThrLysIleLysPheSerAspValLeuHisThrIleLysGluHis                               3853 90395400                                                                  AlaPheValAlaSerGluTyrProValIleLeuSerIleGluAspHis                               405410415                                                                      CysSerIl eAlaGlnGlnArgAsnMetAlaGlnHisPheArgLysVal                              420425430                                                                      LeuGlyAspThrLeuLeuThrLysProValAspIleAlaAlaAspGly                                435440445                                                                     LeuProSerProAsnGlnLeuLysArgLysIleLeuIleLysHisLys                               450455460                                                                      LysLeuAlaGluG lySerAlaTyrGluGluValProThrSerValMet                              465470475480                                                                   TyrSerGluAsnAspIleSerAsnSerIleLysAsnGlyIleLeuTyr                                485490495                                                                     LeuGluAspProValAsnHisGluTrpTyrProHisTyrPheValLeu                               500505510                                                                       ThrSerSerLysIleTyrTyrSerGluGluThrSerSerAspGlnGly                              515520525                                                                      AsnGluAspGluGluGluProLysGluAlaSerGlySerThrGluLeu                                530535540                                                                     HisSerSerGluLysTrpPheHisGlyLysLeuGlyAlaGlyArgAsp                               545550555560                                                                    GlyArgHisIleAlaGluArgLeuLeuThrGluTyrCysIleGluThr                              565570575                                                                      GlyAlaProAspGlySerPheLeuValArgGluSerGluThrPhe Val                              580585590                                                                      GlyAspTyrThrLeuSerPheTrpArgAsnGlyLysValGlnHisCys                               595600605                                                                       ArgIleHisSerArgGlnAspAlaGlyThrProLysPhePheLeuThr                              610615620                                                                      AspAsnLeuValPheAspSerLeuTyrAspLeuIleThrHisTyrGln                                625630635640                                                                  GlnValProLeuArgCysAsnGluPheGluMetArgLeuSerGluPro                               645650 655                                                                     ValProGlnThrAsnAlaHisGluSerLysGluTrpTyrHisAlaSer                               660665670                                                                      LeuThrArgAlaGlnAlaGluHisMetLeuMetArgVa lProArgAsp                              675680685                                                                      GlyAlaPheLeuValArgLysArgAsnGluProAsnSerTyrAlaIle                               690695700                                                                      SerPheArgAlaGluGlyLysIleLysHisCysArgValGlnGlnGlu                               705710715720                                                                   GlyGlnThrValMetLeuGlyAsnSerGluPheAspS erLeuValAsp                              725730735                                                                      LeuIleSerTyrTyrGluLysHisProLeuTyrArgLysMetLysLeu                               740745 750                                                                     ArgTyrProIleAsnGluGluAlaLeuGluLysIleGlyThrAlaGlu                               755760765                                                                      ProAspTyrGlyAlaLeuTyrGluGlyArgAsn ProGlyPheTyrVal                              770775780                                                                      GluAlaAsnProMetProThrPheLysCysAlaValLysAlaLeuPhe                               785790795 800                                                                  AspTyrLysAlaGlnArgGluAspGluLeuThrPheThrLysSerAla                               805810815                                                                      IleIleGlnAsnValGluLysGlnAsp GlyGlyTrpTrpArgGlyAsp                              820825830                                                                      TyrGlyGlyLysLysGlnLeuTrpPheProSerAsnTyrValGluGlu                               8358 40845                                                                     MetIleAsnProAlaIleLeuGluProGluArgGluHisLeuAspGlu                               850855860                                                                      AsnSerProLeuGlyAspLeuLeuArgGlyVa lLeuAspValProAla                              865870875880                                                                   CysGlnIleAlaIleArgProGluGlyLysAsnAsnArgLeuPheVal                               885 890895                                                                     PheSerIleSerMetProSerValAlaGlnTrpSerLeuAspValAla                               900905910                                                                      AlaAspSerGlnGluGluL euGlnAspTrpValLysLysIleArgGlu                              915920925                                                                      ValAlaGlnThrAlaAspAlaArgLeuThrGluGlyLysMetMetGlu                               930 935940                                                                     ArgArgLysLysIleAlaLeuGluLeuSerGluLeuValValTyrCys                               945950955960                                                                   ArgProValProPheAsp GluGluLysIleGlyThrGluArgAlaCys                              965970975                                                                      TyrArgAspMetSerSerPheProGluThrLysAlaGluLysTyrVal                               98 0985990                                                                     AsnLysAlaLysGlyLysLysPheLeuGlnTyrAsnArgLeuGlnLeu                               99510001005                                                                    SerArgIleTyrPr oLysGlyGlnArgLeuAspSerSerAsnTyrAsp                              101010151020                                                                   ProLeuProMetTrpIleCysGlySerGlnLeuValAlaLeuAsnPhe                               1025 103010351040                                                              GlnThrProAspLysProMetGlnMetAsnGlnAlaLeuPheMetAla                               104510501055                                                                   GlyGl yHisCysGlyTyrValLeuGlnProSerThrMetArgAspGlu                              106010651070                                                                   AlaPheAspProPheAspLysSerSerLeuArgGlyLeuGluProCys                                107510801085                                                                  ValIleCysIleGluValLeuGlyAlaArgHisLeuProLysAsnGly                               109010951100                                                                   ArgGlyIl eValCysProPheValGluIleGluValAlaGlyAlaGlu                              1105111011151120                                                               TyrAspSerThrLysGlnLysThrGluPheValValAspAsnGlyLeu                                112511301135                                                                  AsnProValTrpProAlaLysProPheHisPheGlnIleSerAsnPro                               11401145115 0                                                                  GluPheAlaPheLeuArgPheValValTyrGluGluAspMetPheSer                               115511601165                                                                   AspGlnAsnPheLeuAlaGlnAlaThrPheProValLysGlyLe uLys                              117011751180                                                                   ThrGlyTyrArgAlaValProLeuLysAsnAsnTyrSerGluAspLeu                               118511901195 1200                                                              GluLeuAlaSerLeuLeuIleLysIleAspIlePheProAlaLysGlu                               120512101215                                                                   AsnGlyAspLeuSerProPheSerGlyThrSerLe uArgGluArgAla                              122012251230                                                                   SerAspAlaSerSerGlnLeuPheHisValArgAlaArgGluGlySer                               12351240 1245                                                                  PheGluAlaArgTyrGlnGlnProPheGluAspPheArgIleSerGln                               125012551260                                                                   GluHisLeuAlaAspHisPheAspSerArgGluArgAr gAlaProArg                              1265127012751280                                                               ArgThrArgValAsnGlyAspAsnArgLeu                                                 12851290                                                                       (2) INFORMATION FOR SEQ ID NO:3:                                                (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 3893 base pairs                                                    (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                        ATGGCGGGCGCCGCGTCCCCCTGCGCCAACGGCTGCGGGCCCAGCGCGCCCTCCGAAGCG60                 GAGGT GCTGCACCTCTGCCGCAGCCTCGAGGTGGGCACCGTCATGACTTTGTTCTACTCC120               AAGAAGTCGCAGCGGCCAGAACGGAAGACCTTCCAGGTCAAGTTGGAGACGCGCCAGATC180                ACATGGAGCCGCGGTGCGGACAAAATCGAGGGGTCCATCGATATCCGAG AAATCAAGGAG240               ATCCGCCCAGGGAAGACTTCCCGGGACTTTGACCGCTACCAAGAAGACCCTGCCTTCCGG300                CCAGATCAGTCACACTGTTTTGTCATCCTCTATGGAATGGAATTCCGCCTGAAGACCCTG360                AGCCTGCAAGCCACATCTGAGGA TGAAGTGAACATGTGGATCAAGGGCTTAACTTGGCTC420               ATGGAAGATACGCTGCAGGCGGCCACACCCCTGCAAATTGAGAGATGGCTCCGGAAGCAG480                TTCTACTCAGTGGATCGTAACCGAGAGGATCGTATATCAGCCAAGGACCTGAAGAACATG540                CTGTCACAGGTCAACTACCGGGTCCCCAACATGCGCTTCCTCCGAGAGCGGCTGACGGAC600                TTTGAACAGCGCAGCGGGGACATCACCTATGGGCAGTTTGCTCAGCTTTACCGCAGCCTC660                ATGTACAGCGCCCAGAAGACGATGGACCTTCCGTTCTTGGA AACCAACACTTTGAGGACT720               GGAGAGCGGCCAGAGCTTTGCCAGGTGTCCCTTTCTGAGTTCCAGCAGTTCCTTCTTGAG780                TACCAGGGGGAGCTGTGGGCTGTCGACCGGCTTCAGGTGCAGGAATTTATGCTCAGCTTC840                CTTCGAGACCCCTTGC GAGAGATTGAGGAGCCATACTTCTTCTTGGATGAGCTTGTCACC900               TTTCTGTTCTCCAAAGAGAACAGTGTGTGGAACTCACAGCTGGATGCCGTGTGCCCAGAA960                ACCATGAACAACCCACTGTCTCACTATTGGATCTCTTCCTCGCATAATACGTATCTGACT 1020              GGGGACCAGTTCTCCAGCGAGTCCTCCCTGGAAGCCTACGCTCGCTGCCTGAGGATGGGC1080               TGTCGCTGCATCGAGTTGGACTGCTGGGATGGGCCAGATGGGATGCCAGTCATTTACCAT1140               GGGCACACCCTCACCACCAAGATTAAGTTCTCAG ATGTCCTGCACACCATCAAGGAGCAC1200              GCGTTCGTAGCCTCAGAGTACCCTGTCATCCTGTCCATCGAGGACCACTGCAGCATTGCC1260               CAGCAGAGGAACATGGCCCAGCACTTCAGGAAGGTGCTCGGTGACACGCTCCTCACCAAG1320               CCCGTGGAC ATTGCCGCTGATGGGCTCCCTTCTCCCAACCAGCTCAAGAGGAAGATCCTG1380              ATTAAGCATAAGAAGCTGGCTGAGGGCAGTGCCTATGAGGAGGTGCCTACCTCTGTGATG1440               TACTCTGAGAATGACATCAGTAACTCCATCAAGAATGGTATCCTCTACTTGG AGGACCCC1500              GTGAATCATGAGTGGTACCCCCACTACTTTGTTCTGACTAGCAGCAAGATCTACTACTCT1560               GAGGAGACCAGCAGTGACCAGGGAAATGAGGATGAAGAGGAGCCGAAGGAGGCCAGTGGC1620               AGCACAGAGCTGCACTCGAGCGAGAAG TGGTTCCACGGGAAGCTCGGGGCTGGGCGCGAC1680              GGGCGGCACATTGCTGAGCGCCTGCTCACCGAGTACTGCATAGAGACTGGGGCTCCCGAT1740               GGCTCCTTCCTAGTGCGAGAAAGTGAGACCTTCGTGGGGGACTACACGCTGTCTTTTTGG1800               C GGAATGGGAAAGTCCAGCACTGCCGTATCCACTCCCGGCAGGATGCTGGGACTCCTAAG1860              TTCTTCTTGACAGATAACCTTGTCTTTGACTCTCTCTATGACCTCATCACACATTATCAG1920               CAAGTGCCCCTGCGCTGCAATGAGTTTGAGATGCGCCTTTCAGAG CCTGTTCCACAGACG1980              AATGCCCATGAGAGCAAAGAGTGGTACCACGCAAGCCTGACTAGAGCTCAGGCTGAACAC2040               ATGCTGATGCGAGTACCCCGTGATGGGGCCTTCCTGGTGCGGAAGCGCAACGAGCCCAAC2100               TCCTATGCCATCTCTTTCCG GGCTGAGGGAAAGATCAAGCACTGCCGAGTACAGCAGGAA2160              GGCCAGACTGTGATGCTGGGGAACTCTGAGTTTGACAGCCTGGTCGACCTCATCAGCTAC2220               TATGAGAAGCATCCCCTGTACCGCAAAATGAAACTGCGCTACCCCATCAACGAGGAGGCG2 280              CTGGAGAAGATTGGGACAGCTGAACCCGATTATGGGGCACTGTATGAGGGCCGCAACCCT2340               GGTTTCTATGTGGAGGCCAACCCTATGCCAACTTTCAAGTGTGCAGTAAAAGCTCTCTTC2400               GACTACAAGGCCCAGAGAGAGGATGAGCTGACTTTTAC CAAGAGCGCCATCATCCAGAAT2460              GTGGAAAAGCAAGATGGTGGCTGGTGGCGTGGGGACTATGGTGGGAAGAAGCAGCTGTGG2520               TTCCCCTCAAACTATGTGGAAGAGATGATCAATCCAGCAATCCTAGAGCCGGAGAGGGAG2580               CATCTGGATGAG AACAGCCCACTGGGGGACTTGCTGCGAGGGGTCTTAGATGTGCCAGCC2640              TGCCAGATCGCCATTCGTCCTGAGGGCAAAAACAACCGGCTCTTCGTCTTCTCCATCAGC2700               ATGCCGTCAGTGGCTCAGTGGTCCCTAGACGTTGCCGCTGACTCACAGGAGGAGTT GCAG2760              GACTGGGTGAAAAAGATCCGTGAAGTTGCCCAGACTGCAGATGCCAGGCTTACTGAGGGG2820               AAGATGATGGAGCGGCGGAAGAAGATCGCCTTGGAGCTCTCCGAGCTCGTGGTCTACTGC2880               CGGCCTGTTCCCTTTGACGAAGAGAAGATT GGCACAGAACGCGCTTGTTACCGGGACATG2940              TCCTCCTTTCCGGAAACCAAGGCTGAGAAGTATGTGAACAAGGCCAAAGGCAAGAAGTTC3000               CTCCAGTACAACCGGCTGCAGCTCTCTCGCATCTACCCTAAGGGTCAGAGGCTGGACTCC3060               TCCAA TTATGACCCTCTGCCCATGTGGATCTGTGGCAGCCAGCTTGTAGCTCTCAATTTT3120              CAGACCCCAGACAAGCCTATGCAGATGAACCAGGCCCTCTTCATGGCTGGTGGACACTGT3180               GGCTATGTGCTGCAGCCAAGCACCATGAGAGATGAAGCCTTTGACCCCT TTGATAAGAGC3240              AGTCTCCGAGGTCTGGAGCCCTGTGTCATTTGCATTGAGGTGCTGGGGGCCAGGCATCTG3300               CCGAAGAATGGCCGGGGTATTGTGTGTCCTTTCGTGGAGATTGAAGTGGCTGGGGCAGAG3360               TACGACAGCACCAAGCAGAAGAC AGAGTTTGTAGTGGACAATGGACTGAACCCTGTGTGG3420              CCTGCAAAGCCCTTCCACTTCCAGATCAGTAACCCAGAGTTTGCCTTTCTGCGCTTTGTG3480               GTGTATGAGGAAGACATGTTTAGTGACCAGAACTTCTTGGCTCAGGCTACTTTCCCAGTA3540               AAAGGCCTGAAGACAGGATACAGAGCAGTGCCTTTGAAGAACAACTACAGTGAAGACCTG3600               GAGTTGGCCTCCCTGCTCATCAAGATTGACATTTTCCCTGCTAAGGAGAATGGTGACCTC3660               AGCCCTTTCAGTGGTACATCCCTAAGGGAACGGGCCTCAGA TGCCTCCAGCCAGCTGTTC3720              CATGTCCGGGCCCGGGAAGGGTCCTTTGAAGCCAGATACCAGCAGCCATTTGAAGACTTC3780               CGCATCTCGCAGGAGCATCTCGCAGACCATTTTGACAGTCGGGAACGAAGGGCCCCAAGA3840               AGGACTCGGGTCAATG GAGACAACCGCCTCGAAGAATTTTAGTCTAGAAGCTT3893                     (2) INFORMATION FOR SEQ ID NO:4:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 51 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                        CCCGGGC ATATGGATCCATTGGAGGATGATTAAATGGCGGGCGCCGCGTCC51                         (2) INFORMATION FOR SEQ ID NO:5:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 21 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                        CTGCTTCCGGAGCCACCTCTC21                                                        (2) INFORMATION FOR SEQ ID NO:6:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                        (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                       TCGCCATTCGTCCTGAGGGC20                                                         (2) INFORMATION FOR SEQ ID NO:7:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 62 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                        GGGCCCAAGCTTCTAGACTAAAATTCTTCGAGGCGGTTGTCTCCATTGACCCGAGTTCGT60                 CG62                                                                           (2) INFORMATION FOR SEQ ID NO:8:                                               (i) SEQUENCE CHARACTERISTICS:                                                   (A) LENGTH: 26 base pairs                                                     (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                        GATGATGGAGCGGCGGAAGAAGATCG26                                                   (2) INFORMATION FOR SEQ ID NO:9:                                                (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 26 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                        CGATCTTCTTCCGCCGCTCCATCATC26                                               

What is claimed is:
 1. A compound of structural formula I: ##STR11## or a pharmaceutically acceptable salt or ester thereof, wherein: R¹ is: hydrogen;R² is: ##STR12## and R³, R⁴, R⁵ and R⁶ are independently selected from the group consisting of:a) hydrogen; b) halogen; c) C₁ -C₄ -alkyl; d) C₁ -C₄ -alkoxy; and e) hydroxy,provided that at least one of R³, R⁴, R⁵ and R⁶ is a substituent other than hydrogen and where at least R³ or R⁴ is hydrogen.
 2. The compound according to claim 1 which has the formula: ##STR13## wherein:

    ______________________________________                                         R.sup.3        R.sup.4     R.sup.5                                             ______________________________________                                         H              H           OCH.sub.3                                           H              H           Cl                                                  H              Cl          H                                                   Cl             H           H                                                   H              H           CH.sub.3                                            H              H           OH or                                               H              Cl          Cl.                                                 ______________________________________                                    


3. The compound which has the formula: ##STR14## wherein:

    ______________________________________                                         R.sup.3       R.sup.4        R.sup.5                                           ______________________________________                                         H             --Cl           H                                                 H             --OCH.sub.3    H or                                              H             --CH.sub.2 CH.sub.3                                                                           H.                                                ______________________________________                                    


4. A compound of structural formula I: ##STR15## or a pharmaceutically acceptable salt or ester thereof, wherein: R¹ is: ##STR16## R² is: hydrogen; and R³, R⁴, R⁵ and R⁶ are independently selected from the group consisting of:a) hydrogen; b) halogen; c) C₁ -C₄ -alkyl; d) C₁ -C₄ -alkoxy; and e) hydroxy,provided that only one of R³, R⁴, R⁵ and R⁶ is a substituent other than hydrogen.
 5. A pharmaceutical composition for inhibiting phospholipase C comprising a therapeutically effective amount of a compound of claim 1 and a pharmaceutically acceptable carrier.
 6. A pharmaceutical composition for inhibiting phospholipase C comprising a therapeutically effective amount of a compound of claim 4 and a pharmaceutically acceptable carrier. 